Abstract
H2, CO, H2+CO, or a gas consisting mainly of CO and H2 are used as reducing agent of the iron ores.
It is well known that various manufacturing methods of metallic iron, treated iron ores with gases have been recently investigated in Japan as well as abroad.
As a fundamental experiment of manufacturing of iron powder, studies were made on the reduction of hematite powder with H2, NH3 cracking, and C3H8 cracking gases. The results obtained are as follows;
1) The determining step of the reduction with H2 gas is a chemical reaction between H2 gas and iron oxide.
2) In the reduction processes, the reduction velocity is reduced when the Wustite phase appeared.
3) When the iron oxide is cracked, the reduction velocity is accelerated.
4) The use of the temperature range of 550-560°C is advantageous, when the iron oxide powder is reduced with H2 gas.
5) The reduction behaviour with NH3 cracking gas is almost the same as with H2 gas, but the reduction velocity is rather slower.
6) The reduction velocity at the early period is different from that at the later period, during which it becomes faster.
7) The reduction velocity with C3H8 cracking gas is the slowest among those of all the methods used here.
8) When fine hematite powder is sintered at above 800°C, it is necessary to increase the flow rate of reducing gas and to reduce it at about 800°C by the reduction with C3H8 cracking gas.
